I have both a triple on my Riv and a compact on my Salsa cross (in SoCal) and I'm just fine on the compact... The triple is nice sometimes on the Riv, but it weighs 31# also....
You may ask them to swap a 12-28 cogset onto the rear if it doesn't have it already....
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If you have a problem, if no one else can help, and if you can find them, maybe you can hire the A-Team.